Phosphosulfurized esters of amino acids



Un i S s P w 3 164 580 PHOSPHOSULFURIZEIhETERS 0F AMINO A CID S Howard J. Matson, Harvey, 11]., assignor to Sinclair Research, Inc., Wilmington, Del., a corporation of This invention relates to additives for mineral oil compositions and more particularly to oil-soluble agents which impart improved pour point, extreme pressure or loadcarrying characteristics and anti-wear properties to the lubricant.

With the advent of higher compression internal combustion engines, much difiiculty has been experienced in formulating a suitable lubricating oil composition capable of operating under severe conditions to protect-effectively metal surfaces which come in contact with the oil. 7 It is well known that the high pressure occurring in certain types of gears and bearings may cause a film of lubricant to rupture with subsequent damage to the machinery. It has been shown that base lubricants such as mineral oil and/ or synthetic oil can be improved with regard to their protective effect on rubbing surfaces by the addition of certain substances so that excessive wear, scuifing and seizure which normally follow a break in the film of lubricant can be prevented even under the most unfavorable pressure and speed conditions. Lubricants possessing this highly desirable property are called extreme pressure lubricants.

Certain classes of compounds can be used to improve specific properties of base lubricants. Thus, compounds containing sulfur, chlorine, phosphorus or lead or combinations of these elements may improve the extreme pressure properties of a lubricant. However, the simple presence of these elements does not guarantee extreme pressure properties and various compounds that do have these properties can vary considerably in theireifectiv'eness. Itis generally believed that the effectiveness of an extreme pressure additive is related to its ability to reactv with and form a protective coating on a bearing surface to be lubricated. To be most effective, however, the additive must be present in sufficient concentration at the surfaces to form an adequate film. One method of realizing this surface concentration is the use of polar'or other type molecules which have an afiinity or attraction for surfaces. Thus, as opposed to the use of a non-polar.

molecule which will be present in more or less equal concentration throughout the bulk of thelubricant, a polar type molecule will tend to give 'a greater concentration of additive at the metal surface where it is needed.

- In a similar manner a strongly polar material which is not an extreme pressure additive can interfere with the function of a less polar extreme pressure additive. Thus, a strongly polar non-extreme pressure molecule may be preferentially deposited from its admixture withan extreme pressure additive andprevent the extreme pressure additive from forming its protective extreme pressure film.

My invention is directed to a lubricating oil composition containing essentially a major amount of a mineral lubricating base oil and an oil-soluble tetraester of a complex acid and an unsaturated'aliphatic alcohol, which ester has been phosphosulfun'zed. This tetraester additive has been found to improve pour point, load-carrying and anti-wear properties of lubricating oils. Thus, theester reaction product of a complex acid such as ethylene diamine tetraacetic acid, which contains sulfur and phosphorus and several polar groupings in the same molecule, has been found to provide a lubricant additive having advantageous anti-wear and extreme pressure characteristics.

The ,tetraester is formed from carboxylic acid groups preferably of lower aliphatic acids such as acetic, propionic, ,butyric, and the C and C aliphatic acids and an unsaturated aliphatic alcohol generally having about five carbon atoms or more. In general the acid has the molecular structure:

HOOC-R HO 0 0-K N-CHg-QHr-N n0oo om CHr-COOH CH2COOH The ethylene diamine tetraacetic acid used in forming the reaction products in an efiicient chelating agent; that is, a chemical which complexes polyvalent metallic ions with a multi-ringstructure that inactivates the metal. This property has been used in a variety of applications' The unsaturated aliphatic alcohols of the present invention generally have about 4 to 22, preferably about 8 to 20, carbon atoms and include unsaturated cycloaliphatic alcohols such as cycloalkenols and less desirably aromatics having unsaturated acylic or cycloaliphatic substituents. These alcohols have an unsaturated or double bond between acylic or cycloaliphatic carbon atoms with the alcohol hydroxyl group also being'attached to the same acylic or cycloaliphatic carbon chain. The preferred alcohols are the unsaturated acylic aliphatic alcohols as, for example, trimethyl pentenol-Z, 2-ethyl hexenol-l, zoomaryl alcohol, etc. It should be emphasized that saturated alcohols are unsuitable for use in the present invention since phosphosulfurization of the tetraester produced from the acids of the present invention and saturated alcohols results in a reaction product which is unstable in lubricating oils, effecting cloudy blends that eventually form voluminous precipitates.

In making the ester the appropriate acid and methanol are mixed, and the solution is refluxed and heated for the necessary period of time to obtain esterification. The time of refluxing is related to the particular constituents employed and is not considered critical. The period of time will generally range from about 2 to 14 hours. After such as iso-butanol along with a catalyst such as tetra octylene glycol titanate is added to facilitate transesterification. The constituents are heated for approximately 5 to 8 hours at a temperature of about to about'140" C. The product thus obtained is added to a higher molecular weight unsaturated aliphatic alcohol and a solvent such as xylene, and a catalyst such as octylene glycol titanate is added to facilitate ester interchange. The reaction is now maintained at a temperature from about to 160 C. for a period of from about 5 to 10 hours. The solvent is then removed by distillation.

The tetraester of the acid thus obtained is phosphosulfurized by the addition of phosphorus and sulfur compounds such as P 5 P 8 P 8 and the like. The subsequent heating and filtering completes the reaction and facilitates the recovery of the final product. The temperature for phosphosulfurizing can vary from about to 450: F. with the preferred temperature being about 250 to 300 F. Generally in preparing the additive I may be employed. A particularly suitable base oil used. in the'preparation of the compositions described hereinafter is a solvent treated Mid-Continent neutral having a viscosity index of about 95.

The amount of reaction product added to the lubricating oil is suflicient to impart extreme pressure and anti-wear properties to said oil. Thus, the amount of ester added can vary in amount depending upon the par,- ticular characteristics of lubricating oil utilized. In general from about 0.1 percent of the phosphosulfurized reaction product by weight to about 10 percent of the final composition by weight is utilized in my lubricating oil composition withva preferred amountof from about 1 to 5%. 7 Although my additive has been described as the tetraester it may contain portions of lessesterified materials such as di and tri-esters 7 My composition can also contain other additives'such as anti-oxidants, anti-foaming agents, etc.

The following examples, not to be construed as limiting,

are ordered to further illustrate the novel additive and" lubricating oil composition of my present invention.

Example I 73 grams of ethylene diamine tetraacetic acid are added to 320 grams of methyl alcohol and refluxed with stirring for a period of about 3 hours. HCl is then added and the mixture is refluxed for about 8 hours and then the reaction product is recovered and the excess alcohol is distilled off. The light amber, viscous product is found to be insoluble in mineral oil, di-Z-ethylhexyl)-sebacate, toluene and 2-ethylhexanol, but soluble in iso-butanol. 225 grams of iso-butanol and 1 gram oftetra-octylene glycol titanateyare added to the above product to facilitate ester interchange. The reaction is maintained at approximately 130 C. :for a period of about 6 hours. This is accomplished by gradually removing reflux as distillate during the above period. The product is analyzed to be 3.87% nitrogen; Next 255 grams of the tetrabutyl ester of ethylene diamine tetraacetic acid is added to 530 grams of an unsaturated alcohol known as Makanol 8 (Makanol 8 is described as an alcohol resulting from the sodium reduction of soybean oil and consists of 12% saturated and 88% unsaturated fatty alcohols having an average molecular weight of about 265). Then 500 ml. of xylene solvent and 5 grams of tetra-octylene glycol titanate were added to facilitate ester interchange. The temperature is then maintained at about 150 C. for about 8 hours. The solvent is then removed by vacuum distillation at a temperature of about 13160" C. The product thus formed can be called Product Example 11 About 264 grams of Product A is added to about 36 grams of sulfur and then reacted *for about 24 hours at an approximate temperature of 320 F. The product thusobtained is called Product B.

Example III grams of concentrated.

300 F. for about 16 hours. The reaction mixture is then filtered to yield approximately 418 grams of a bright yellow viscous liquid analyzed as containing sulfur, 0.92%; phosphorus, 1.07%. This product is called Prodnot C.

' Example IV Shell 4-Ball Wear Test Mean Hertz Load SAE Load Test Falex Load Test Timken L-20 Test These tests have been fully described in literature under the subject of anti-wear and extreme pressure testing. Thus, I will not attempt to go into any detail concerning the procedures of each. The possible exception to the above is the Timken L-20 Test which is run using the Timken machine described in CRC Ll8545. The test block is continuously moved back and forth beneath the test cup in a direction paralleling the level arm for a distance for about 0.13 inch at an approximate rate of about 4 times per minute. Conditions for load, speed, time and temperature may be varied and are noted for each given test.

The/following table reveals results and comparisons between similar tests on a base oil, a conventional motor oil additive and my products. The base oil is a Vi solvent refined Mid-Continent neutral oil having a viscosity of about 33 SUS at F. The motor oil additives included about 3 percent of a solution of 15 weight percent basic barium mahogany sulfonate in petroleum oil along with 1.8 percent of 50 percent Zinc dithiophosphate diester in petroleum oil. Products C and'D were readily soluble in the base oil and each produced clear blends.

Blend No -1 2 3 4 Base Oil, Wt. percent 100 95. 2 98 98 Motor Oil Additiv 4.8 .1 Product 0. 2.0 Product D 2; 0 Shell d-Ball Wear Test, Sear Diam., mm. (7 kg, 2 hrs, 0., 640 r. .rn) 0, 687 0. 247 0. 290 0. 280 Mean Hertz Load 13. 7 26. 9 33.8 40. 7 SAE at 300 r.p.rn., l 67 121 132 Falex Breakdown, lbs Fails 1, 600 4, 500 3, 750 Tilnken L-20 Test, Total wear, mg: at

(100 lbs. 200 F., 200 r.p.m., 16 Start hrs.) of 254 14.1 12.5 lbs. 200 F., 200 r.p.rn. 16 Test hrs. 14. 3 Pour Point of Blend, F 10 10 15 10 The above data demonstrate the improved pour point, the increased load carrying capacity and extreme pressure properties of my compositions.

This'application is a division of serial No. 207,807, now Patent No. 3,097,170, a continuation-in-part of my now abandoned application Serial No. 752,409 filed August 1,-1958.

- I claim:

, 1. A phosphosulfurized mineral oil-soluble tetraester of an unsaturated aliphatic alcohol of from 4 to 22 carbon atoms having carbon to carbon double bond unsaturation only and a carboxylic acid of the formula:

5 wherein R is a divalent hydrocarbon radical of 1 to 5 of an unsaturated aliphatic alcohol of 8 to 20 carbon carbon atoms and R is a divalent hydrocarbon radical atoms having carbon to carbon double bond unsaturation 2 to 6 carbon atoms said phosphosulfurized tetraester y and ethylene diamine tetfaacetic acid Said P p being the reaction product of said tetraester and about 1 Sulfurized tetraestel' being the reaction Pmdllct Of Said to 10% by Weight of a phosphosulfurizing phosphorus- 5 tetra-es te r and about 1 to 10% b Wight of a P p sulfur compoun sulfunzing phosphorus-sulfur compound.

2. A phosphosulfurized mineral oil-soluble tetraester No references cited. 

1. A PHOSPHOSULFURIZED MINERAL OIL-SOLUBLE TETRAESTER OF AN UNSATURATED ALIPHATIC ALCOHOL OF FROM 4 TO 22 CARBON ATOMS HAVING CARBON TO CARBON DOUBLE BOND UNSATURATION ONLY AND A CARBOXYLIC ACID OF THE FORMULA: ((HOOC-R)2-N)2-R'' WHEREIN R IS A DIVALENT HYDROCARBON RADICAL OF 1 TO 5 CARBON ATOMS AND R'' IS A DIVALENT HYDROCARBON RADICAL 2 TO 6 CARBON ATOMS SAID PHOSPHOSULFURIZED TETRAESTER BEING THE REACTION PRODUCT OF SAID TETRAESTER AND ABOUT 1 TO 10% BY WEIGHT OF A PHOSPHOSULFURIZING PHOSPHORUSSULFUR COMPOUND. 